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Chapter 2
Themes
Key
LitCharts assigns a color and icon to each theme in The Origin of Species, which you can use to track the themes throughout the work.
Natural Selection and the Power of Nature
Reason, Argument, and the Scientific Method
Time and Progress
Collaboration and Science
Summary
Analysis
Darwin wrote about his intention to examine how the struggle for existence affected natural selection. He believed that because of each species’ struggle to survive, even light variations in a species help the offspring to survive. This process of preserving small, helpful variations is natural selection.
This is the part of Darwin’s theories that is most influenced by Thomas Malthus (the famous economist and political theorist whom Darwin mentions in the introduction). Malthus believed that populations grow faster than food supplies, and that as a result, a population would start to die off once it exceeded the available food reserves.
Themes
Literary Devices
The Term, Struggle for Existence, used in a large sense. Darwin clarified that when he used the term “struggle for existence,” he meant it not just in the literal sense but also in the metaphorical sense. He clarified that he didn’t just mean dogs literally fighting over food, but also cases like desert plants that “struggle” to get enough moisture.
As with most chapters, Darwin spends the early part of this chapter defining terms and setting the parameters of what he’ll cover over the course of the rest of the chapter. Here he clarifies that not all “struggles” are physical combat and that in some ways, he uses the word as a metaphor.
Themes
Geometrical Ratio of Increase. Darwin noted that every organism encounters some form of destruction in its lifespan. Otherwise, its population would increase geometrically and quickly outgrow available resources, similar to what Thomas Malthus wrote about. Darwin had evidence from humans and domestic animals of just how quickly populations could increase under favorable conditions. But while many plants and animals have the potential to grow this rapidly, it is rarely the case. Factors like food scarcity and climate all contribute to “destruction” that prevents rapid, endless increases.
The concept of populations growing at a geometrical rate is one that Darwin borrows directly from Thomas Malthus. But while Malthus was primarily thinking about human populations, Darwin’s innovation is to expand the idea beyond human populations and to consider how similar principles might be applied to organisms in nature.
Themes
Nature of the Checks to Increase. Darwin admitted that the “checks” which stopped a population from increasing at a rapid rate were not always clear or easy to determine. The food supply is one obvious, extreme limit, but more often the size of a species is limited by predators. Climate also restricts population growth, with extreme cold and droughts being particularly effective at checking growth.
Darwin explored the different factors that could stop a population from growing. These factors are important because the adaptations that arise through natural selection help a species to better overcome these factors.
Themes
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When a species experiences very favorable conditions and grows rapidly in a small area, it often faces other checks, such as an epidemic, that help keep the population size under control. In other cases, a species population must be large in order to survive its predators—for example, corn must produce a lot of seeds to account for how many seeds get eaten by birds.
Darwin provides examples of how some populations grow quickly under the right conditions. Nevertheless, if a population keeps growing geometrically, eventually it will hit barriers to growth. While Malthus wrote about limited food supplies, here Darwin considers other important limits: disease and predators.
Themes
Complex Relations of all Animals and Plants to each other in the Struggle for Existence. Darwin noted how the populations of plants and animals are often checked through their relationships with each other. For example, in some areas, cattle stop Scotch fir trees from growing because they eat the saplings, but once the cattle are enclosed, the Scotch firs spring up. These relationships between species can take many forms and be affected by other factors like geography, climate, and seasons.
Species don’t exist in a vacuum, and so in this passage, Darwin explores how the success or failure of one species in an area can affect the population of another species. Two species do not have to be directly competing for resources to be related. For example, in this passage the Scotch fir are not competing with the cattle for food, but their populations are nevertheless closely intertwined.
Themes
Struggle for Life most severe between Individuals and Varieties of the same Species. Darwin asserted that the more similar species are, the more directly they will be in competition with each other. Even very different species can have similarities, however, and the claws of a tiger are not so different from the claws of a parasite riding on the tiger.
Despite the example of cattle and Scotch fir in the previous section, however, Darwin argues that the fiercest competition is among creatures that are most similar. This makes sense, because individuals of the same species have the same needs and are therefore often in competition for them.
Themes
Darwin suggested that his audience should try to imagine what could happen to give one species an advantage over another. He argued that every living thing is struggling to try to increase its population at a rapid rate, but that in the pursuit of this, it will also experience occasional destruction. While this could seem dark, Darwin took it as a consolation that ultimately “the vigorous, the healthy, and the happy survive and multiply.”
By this point in the book, Darwin has not yet fully laid out his theory of natural section, but he continues to build it part by part. In this chapter, he aimed to convince audiences beyond any doubt that organisms in nature are in a constant competition to survive, and that those best adapted to their environment are the ones that, in most cases, will survive.
Themes
